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	for linux-mtd@lists.infradead.org; Wed, 23 Apr 2008 12:23:23 +0000
Subject: Re: [RFC] slight UBI scan time improvement
From: Artem Bityutskiy <dedekind@infradead.org>
To: Nancy <nancydreaming@gmail.com>
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Date: Wed, 23 Apr 2008 15:23:55 +0300
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On Wed, 2008-04-23 at 18:51 +0800, Nancy wrote:
>       Will you please explain why need leb_read_lock()?

This locks the LEB and prevent concurrent I/O to this LEB. E.g., we do
not want a situation when one process unmaps an LEB while another
process is writing to it.

That was probably overkill, but I implemented per-LEB r/w locking. This
is similar to rw semaphore in Linux. It means that several processes may
simultaneously read for this LEB, but only one process at a time may
write (or unmap).

>       If I ummap a leb(only operate the eba table, do not do
> ubi_wl_put_peb() ), then, what will that PEB belong to? wl->free,
> wl->used, wl->prot.pnum, wl->prot.aec, wl->scrub? What will happen to
> that PEB?

If you unmap it you have to clean the corresponding EBA table record and
return it to the WL unit.

--=20
Best regards,
Artem Bityutskiy (=D0=91=D0=B8=D1=82=D1=8E=D1=86=D0=BA=D0=B8=D0=B9 =D0=90=
=D1=80=D1=82=D1=91=D0=BC)